Reducing
Reducing
(OP)
Hi,
I have a project to remove a number of rooftop AC units, with their duct-mounted hot water coils, in order to replace with newer gas-fired units.
There is one heating water circuit serving these HW coils, and another circuit, with a much smaller head and flowrate, on same circulating pump.
Would it be best to replace the pump or could this situation be taken care of with a bypass across pump including a balancing valve?
thank,
caluna
I have a project to remove a number of rooftop AC units, with their duct-mounted hot water coils, in order to replace with newer gas-fired units.
There is one heating water circuit serving these HW coils, and another circuit, with a much smaller head and flowrate, on same circulating pump.
Would it be best to replace the pump or could this situation be taken care of with a bypass across pump including a balancing valve?
thank,
caluna





RE: Reducing
Friar Tuck of Sherwood
RE: Reducing
there is yet another pump loop with its own inline pump-but none of that part will change. (That pump is 25 gpm 40' head)
Both pumps are fed off a a header which comes from a steam/water heat exchanger.
I know I will have to change something here, but was hoping to make do with bypass line or new pump (and just have reduced flow from heat exchanger). Am not too sure how reducing one of the (essentially "parallel") loop flows would affect the whole.
RE: Reducing
Alternatively, isolate the dead leg and fit a VSD on the pump. The flow is about 12l/sec which is a fairly large flow rate...I guess you have pipework over 4" diameter and a fairly big motor rating (perhaps 5.5kW)
You really need to do a costing exercise and weigh the cost of either...
a. Simple bypass and an oversized pump running and wasting energy
b.Fitting an inverter drive (and isolating the dead leg.
c.Fitting a new reduced duty pump.
If initial costs are the driving force, then I would guess a is your choice.
Friar Tuck of Sherwood
RE: Reducing
RE: Reducing